Glass may be colored by titania and silver oxide, and the authors made the experiments in order to know the mutual action on the coloring of glass.
Specimens were prepared by adding titania to the maximum limit of glass formation and a small amount of silver oxide to the six kinds of the basic glasses of the systems; silicate, borosilicate, borate, and phosphate.
The silicate, borosilicate and borate glasses showed the rapid and stable development of brown to deep red colors even by quenching, which, however, showed no change of color by reheating.
Phosphste glasses were colored purple, which also showed no further color development by reheating. The former gave the absorption at 460mμ, while the latter did not show this absorption due to the separation of Ag.
The authors attribute the rapid separation of silver to the thermal change of the equilibrium
Ti³⁺_??_Ti⁴⁺
which acts as a thermoredusing agent during the cooling of glass, and accordingly the reaction
Ag⁺+Ti³⁺→Ag°+Ti⁴⁺
takes place.
The change of the absorption spectrum from ordinary silver containing glasses may be interpreted by the separation of TiO₂ around the micro-crystal of silver.

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Izumiyama pottery stone occurs in the vicinity of Arita-cho locating in north Kyushu area. The mass deposits composed of quartz and sericite containing an extremely small amount of pyrite and alum, and partly bring with orthclase, albite and kaolinite.
The radial distribution of companion minerals form approximetely a concentric circles, the center of the mass being rich in feldspar near the surface, and in sericite near the center. These change reflects on the thermal properties of the stone.
The chemical composition of sericite belongs, in this case, to the type in which the amount of the exchange of K₂O by H₂O is small. Hence the pottery stone has low refractivity.

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The conventional method of measuring dielectric constant can not be applied to powder such as synthetic mica which is difficult to obtain a large specimen, or it leads to a result with large error.
The authors have deviced a powder method, which measures the dielectric constant of the specimen obtained by mixing a known amount of paraffin, and from which the value of 100% sample is worked out using a formula.
For such purpose the logarithmic formula of Lichtnecker gave the best results also for the powders of natural mica and glass. The formula accords approximately with one derived from the model which assumes the particles are coming together at the center.
The dielectric loss of composite body is represented by an equation of first degree, which, however, has a trend of giving some what higher value.

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This paper concerns with an self recording analyser of particle size distribution of the construction being so simple that may be installed conveniently an any laboratory.
The apparatus is equipped with a glass lever, and the gain in weight of the particles accumlated on the weighing pan is recorded automatically with a displacement meter of differential transformer. It records simultaneously the three different size distributions of three samples.
The authors have carried out the measurements of the particle size distributions of some clays with satisfactory results.

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In the process of cleansing there appeared minute cracks on the surface of bottles after they were steeped in soakers; the phenomenon which is likely to occur after many hours of steeping.
The experiments concerning this matter gave following results:
(1) As it was expected, the cracks occur generally in the soakers containing the solution of alumium compounds.
(2) The trend was found that the cracks appear more frequently on carbon-sulpher amber than mangan brown bottles.
(3) Comparing the difference in the composition between the carbon amber and mangan brown bottles it was found that, in general, the former was rich in SiO₂ and contained a small amount of SO₃, while the latter was rich in Fe₂O₃, MnO and Al₂O₃.
(4) In the powder test of durability against acid and alkali the mangan brown bottles gave the better results than those of carbon amber.
(5) The outbreak of cracks can be prevented effectively when the bottles are turned out from a lehr in which they are kept in contact with the current of CO₂, and SO₂.
(6) By scraping test it was observed that there existed a trend of producing cracks as far as 0.1-0.2mm from glass surface, which, however, decreased toward the middle.
(7) The presence of Be, Zn, and Al ions in the soaker solution was found to prevent the reduction of bottle weight, but to promote the outbreak of cracks.

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